17 Jun 2016 |
World innovation news |
Materials & Manufacturing
First Bioplastic to be 100% Biodegradable and a Natural Fertilizer
Four hundred and fifty years is the time needed for a polyethylene plastic bag to decompose in nature! According to a study from Jenna Jambeck, environmental engineer from the University of Georgia, each year, nearly 8.8 million tons of plastic end up in the oceans, threatening marine life. So, why do we still use this type of plastic?
Researchers at Harvard’s Wyss Institute studied this issue and introduced a new bioplastic: the first to be 100% biodegradable and which also produces a natural fertilizer.
These researchers propose to use shrimp shells, specifically chitosan, a form of chitin which is the second most abundant organic material on Earth, as a substitute to plastic.
Chitosan, a tough polysaccharide, is the main ingredient in the shells of crustaceans, the armorlike cuticles of insects, and also the wings of butterflies. This substance was originally combined with the silk fibroin protein to form a new bioplastic called “Shrilk” – a contraction of “shrimp” and “silk”. Finally, as Shrilk is not waterproof like petroleum-based plastics, a coating of beeswax was added to provide a water barrier.
The raw material to produce this bioplastic would come from the “waste” of shrimp producers. It takes, for example, 200 grams of shrimp shells – or a handful – to produce a glass.
The Wyss Institute team developed a new way to process this bioplastic, making it even cheaper and easier to make. According to the Institute, “the novel fabrication method preserves the strong mechanical properties of chitosan, resulting in a tough, transparent material that can be used to fabricate large 3D objects with complex shapes using traditional casting or injection molding manufacturing techniques”. This means objects made from Shrilk can be mass-manufactured and will be as robust as objects made with the everyday plastics used in toys, television, cell phones,etc.
Shrilk is fully biodegradable, but it also breaks down into the environment after two weeks and releases plant nutrients into the soil that support plant growth.
The director of the institute, Donald E. Ingber concluded: “Our scalable manufacturing method shows that chitosan, which is readily available and inexpensive, can serve as a viable bioplastic that could potentially be used instead of conventional plastics for numerous industrial applications.”